To maintain leadership position, Apple will apparent improves a couple features. Graphics and display resolution are the most obvious choices. They have direct impact to user experience.
The question comes to whether these improvement will really provide a substantial benefit to users. I can see benefit on watching 1080p video. What else? Are you looking forward to better resolution and better graphic engine?
It's odd that Apple increased the pixel density because on the web most images are sized at 72 dpi and I don't see any pixels, so why push Resolutionary? If I cannot see any visual difference, then why use that as your marketing differentiator?